Fujitsu FR81S Manuale Utente
CHAPTER 41: CAN
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: CAN
FUJITSU SEMICONDUCTOR CONFIDENTIAL
74
5.3.6. Reception Message Processing
Reception message processing is shown.
CPU can read reception messages at any time via the message interface register.
Generally, "007F
H
" is written to the IFx command mask register (IFxCMSK). Message number of the
message object will then be written to the IFx command request register (IFxCREQ). By using this
procedure, reception message of the specified message number will be transferred from message RAM to
the message interface register. At this time, the NewDat bit and IntPnd bit of the message object can be
cleared to "0" by the setting of the IFx command mask register (IFxCMSK).
The message will be received if it matches the acceptance filter. If the acceptance filter mask is used in the
message object, the data that has been set as a mask will be excluded from the acceptance filter, and the
decision of whether or not to receive the message will be made.
The NewDat bit indicates whether a new message has been received after the message object was last read.
The MsgLst bit indicates that the next reception data has been received before the previously received data
is read from the message object, resulting in the loss of the previous data. The MsgLst bit will not be reset
automatically.
The TxRqst bit will be cleared to "0" automatically when a data frame matching the acceptance filter is
received while the remote frame transmission is being processed.
MB91520 Series
MN705-00010-1v0-E
1767